Thank you for help. Sry for answering so late, I attened a funeral today.
I will try Bullet (I used it for another game and it was really good) again.
Otherwise I try another solution i found out yesterday:
Get all blocks you are sorrunded with a distance of three blocks. Do a d3dxboundingboxtest. All boxes that collide with the ray, do a d3dxintersecttri test.
So i know which surface my ray is intersecting.